I have a 2020 Marin Rift Zone that came with Eagle SX. The BB is a powerspline (I assume Truvativ but I haven't taken it out). In the process of chasing down a shifting issue (turned out to be a limit screw issue) I noticed that while pedaling backward there is a sound kind of like a train going down the tracks (like a thumping). Is this the bearings in the BB going bad already? I know these are not known for being durable but I thought I would get more than a half season out of it (I didn't really ride this bike until this year).